Potential for enhanced soy storage protein breakdown and allergen reduction in soy-based foods produced with optimized sprouted soybeans

In this study, potentials for improved soy storage protein breakdown and allergen reduction in soy-based foods produced with soybeans sprouted at optimized conditions was investigated using proteomic approach. The changes in protein concentration and expression levels of six sprouted soy-based foods, namely SSM: sprouted soymilk, STC: tofu from sprouted soybeans coagulated by CaCl2, STH: tofu from sprouted soybeans coagulated with Hibiscus sabdariffa flower extracts, SFS24: sprouted fermented soymilk (24 h), SFS48: sprouted fermented soymilk (48 h) and SSK: sprouted soymilk-kefir and their respective control samples (USM, UTC, UTH, UFS24, UFS48 and USK) were analyzed using 2-dimensional gel electrophoresis and PDQuest image analyses. Protein concentration significantly increased in sprouted products (up to 149% in SSK). Eight differentially expressed protein spots were selected and identified by MALDI- TOF/TOF mass spectrometry as glycinin G2 (Gy2) subunit B1a, β-conglycinin (α, α′ and β subunits), trypsin inhibitor, 34 kDa soy seed protein and sucrose-binding proteins. Higher extent of breakdown of soy storage protein was obtained in sprouted soy products, as shown by higher protein concentration and spot volumes. Lower spot volumes were obtained in all fermented products. This study suggests higher potentials for soy storage protein breakdown and reduced allergen contents in sprouted soy-based foods.